ABANDONED. Juvenile fiction, boy with memory loss and multiple personalities

[Tiffany]

I this book sometime in the 1980s. The boy describes "waking up" on his birthday but he's lost two years to memory loss and doesn't know why . He later discovers he has multiple personalities.

I can't find it any any of the popular lists about dissociative identity disorder fiction or multiple personality fiction. It's not any of the famous autobiographies and it is not Picture Perfect.

Anyone recognize this at all?

[Kris]

A guess - Triple Boy by Dale Carlson?

What caused his multiple personalities? Spoilers are fine in a post (not the header) - just give us a clear warning before revealing a spoiler (e.g., use the Goodreads spoiler link).

[Lobstergirl, au gratin]

Tiffany, are you still looking for this or did you find it?

[Kris]

No response, moving to Abandoned folder.

Tiffany (OP) was last active on the site in May 2017.